Fuse elements, such as fuse links and program transistors, are programmable electronic devices that are employed in a wide variety of semiconductor applications. For example fuse links and program transistors may be employed to enable redundant memory cells in a memory array, to program a chip identification, or to customize integrated circuits after production.
A fuse is normally closed or linked. Programming the fuse means opening or blowing a fuse link located in the fuse, which results in a significant increase in resistance. In contrast an anti-fuse is normally open, e.g., the fuse has a capacitor like structure. Programming the anti-fuse means closing the capacitor like structure of the anti-fuse which results in a short or decrease in resistance.
There are several different types of fuses and anti-fuses. One type of conventional fuse includes an electrically programmable fuse. This electrically programmable fuse may include a polysilicon/silicide stack. The polysilicon/silicide stack typically includes polycrystalline silicon and an overlayer of silicide.